Porous high density polyethylene (PHDPE) coated tooth roots which have successfully served as abutments for individual free standing posterior teeth in dogs will be employed as abutments for free standing anterior and posterior teeth, and as distal abutments for 3 unit posterior bridges in monkeys. One objective is to determine if the biological response of the primate alveolar bone to the PHDPE coated tooth roots is similar to that of the dog. Previous studies using porous titanium implants of a similar design suggest that more bone forms in the primate implants than is formed in canine roots. It will be important to establish if there is a species difference in the biological response to porous artificial tooth roots. A second objective is to determine whether implants which have functioned successful as free standing single posterior tooth replacements in masticatory function can serve as well under occlusal function (as abutment for bridgework) and can serve in areas which receive higher lateral loads (anterior teeth). A third objective of the present research is to delineate the modes of failure of the porous coated tooth roots. The study will primarily address two potential modes of failure; catastrophic mechanical failure due to masticatory loads which cause failure at the PHDPE/bone interface and periodontal disease processes. The former mode of failure will be investigated experimentally by loading to failure eight in plants each at 3 and 12 months. Periodontal disease processes will be identified using transmission electron microscopy in conjunction with histological evaluation of specimens obtained by biopsy and autopsy. A final objective is to determine if the mechanical properties of the porous coating (e.g., modulus of elasticity) influence the biological response and hence clinical performance of the implants. This objective will be achieved by comparing results of the PHDPE studies with results of studies of porous titanium implants having the same design (these latter studies are presently being conducted in the principal investigator's laboratory under another NIDR research grant).